Smart cards are small electronic devices that may be used to store, process, and transmit information and data. Smart cards are increasingly being used in a wide variety of applications including healthcare, banking, entertainment, transportation, food and product packaging, e-commerce, and personal identification. In one such application, smart cards are used to record and monitor various conditions and events. In many industries involving products that are sensitive to specific conditions it may be desirable to monitor environmental conditions, such as temperature, to which the products have been exposed. In particular, smart cards have found increasing use in the food industry to record and monitor conditions under which items such as perishable goods have been shipped and/or stored. Typical measurements may include temperature, relative humidity, light intensity, on/off, open/closed, voltage, pressure, and events over time. Smart cards may be programmed to take specific measurements at desired time intervals. Smart cards that are capable of measuring and recording one or more environmental conditions are commonly referred to as “data loggers.”
Smart cards are typically about the size of a credit card and include a housing in which one or more electronic components are disposed. The electronic components may include a processor, electronic data memory, one or more sensors, a data display, and combinations thereof. In some smart cards, the electronic components may include an integrated circuit chip. Smart cards may include a battery component that provides power to the various electronic components. Smart cards for environmental monitoring may include one or more sensors that are capable of monitoring environmental conditions to which the smart card has been exposed.
Smart cards are typically used with a reader/writer that includes an external interface that is able to transmit information to or from the smart card. Some smart cards include electrical contacts or terminals which are used to make a direct electrical connection between electrical circuitry on or within the smart card and the external interface. Other smart cards may include a radio frequency (RF) antenna that can be used in combination with an external interface to communicate with an external interface. Communication between the smart card and an external interface may be used to activate, program, and send or retrieve data to and from the smart card. The use of radio frequency identification (RFID) technology in smart cards may help facilitate communication between the smart cards and an external card reader.
In some smart cards, the various electronic components may comprise flexible structures upon which electronic circuitry, e.g., processor, memory, and/or RF antenna, may be disposed. Such flexible circuits may comprise a polymeric substrate having electronic circuitry thereon. The electronic components typically include electrical contacts, e.g., electrically conductive traces, electrically conductive bond pads, terminal points, that are arranged so that the components may be electrically interconnected with each other.
In some previous flexible structures having two or more electronic components, electrical interconnection has been made between the devices by soldering or welding the respective electrical contacts together, or by attaching the respective electrical contacts with an electrically conductive adhesive. However, when the flexible structure is bent, the relatively rigid (as compared to the flexible structure) solder, weld or adhesive can break, resulting in failure or degradation of the electrical interconnection. Further, soldering or welding the respective electrical contacts together requires additional labor and materials, which may result in increases in cost. Additionally, many flexible electronic components may be made of low temperature plastic which undesirably melts at the temperatures necessary for soldering, welding or heating with an adhesive.
In some previous flexible structures having two or more electronic components, electrical interconnection has been made by forming holes through the main body of the card, the holes extending between the respective electrical contacts of the devices, then inserting conductive “studs” into the holes which are attached at either end to the respective electrical contacts by soldering, welding or use of an electrically conductive adhesive. However, when the flexible structure bends, the conductive studs do not, which may result in one or more of the studs breaking away from one or both of the electrical contacts, thereby breaking the electrical interconnection between the devices.
Thus, there still exists a need for an improved method of electronically connecting flexible circuits that provides simplicity and reliability.